The long term objectives of this project are (1) to document the pre-and postnatal development of the metabolism of vitamin B-6, using pigs as animal models (2) to determine the relationship between the maternal and fetal/newborn metabolism of vitamin B-6 in pigs and humans, and (3) to compare the effectiveness of use of erythrocyte pyridoxal 5'-phosphate (PLP) concentration and hemoglobin-oxygen binding affinity as status indices of vitamin B-6 compared to other indices such as plasma PLP concentration and erythrocyte transaminase activities. currently, there is increasing uncertainty over how to accurately determine the vitamin B-6 nutritional status of population groups with altered concentrations of plasma PLP, including pregnant and lactating women, and premature and full-term infants. In order to better understand the basis for fluctuating concentrations of plasma and erythrocyte PLP, we propose to document developmental changes in the concentrations of B-6 vitamins and activities of vitamin B-6 metabolizing enzymes in pregnant and lactating sows and their pre- and postnatal piglets, as experimental animal models. This swine study will be integrated with a human study which will investigate the developmental changes in the concentrations of B-6 vitamers and the activities of vitamin B-6 metabolizing enzymes in pregnant and lactating women and their full-term breast-fed infants. Additionally, we propose comparing existing vitamin B-6 nutritional status indices in both the swine and human studies with two potential new indices of erythrocyte PLP concentrations and the erythrocyte hemoglobin-oxygen binding affinity.